As use of smart phones, tablets, and other Internet-enabled mobile devices increases, mobile operators are facing the tremendous challenge of coping with rapid data traffic growth stemming from bandwidth-intensive Internet services, such as video streaming. Major problems may occur in the mobile operators' aggregation and core transport network due to the common centralization of mobility gateways (mobility anchors) close to the Internet Exchange (IX) peering point(s). Mobility gateways represent the topological anchor of a mobile device's IP address and ensure forwarding of data packets to/from the mobile device's current location to any correspondent node. All traffic from and to a mobile device traverses the device's mobility gateway, from there traverses the core network.
To reduce traffic volume and associated costs in the mobile operator's core network, standards development organizations, such as the 3rd Generation Partnership Project (3GPP) and the Internet Engineering Task Force (IETF), are working on technology to enable decentralized mobility management by means of distributed mobility gateways (DMM, Distributed Mobility Management) or Traffic Offload Functions (TOF). Distributed Gateways or Traffic Offload Functions enable cost-constrained assignment of a Gateway/TOF to a user's mobile device, since the distance and the associated routing path between a user's device and its assigned gateway/TOF can be kept short. Complete de-centralization of mobility gateways may lead to placement of gateways into the backhaul network (i.e., the portion of the network that includes the intermediate links between the core network, or backbone, and the subnetworks at the “edge” of the network) or even closer towards the edge of the network—e.g., towards the radio access for mobility devices. Such a setup potentially keeps transport costs between a mobile device and its gateway small, but may also have some drawbacks. For example, the closer the gateways are positioned to mobile devices, the more often a new gateway may need to be assigned due to the device's mobility pattern to maintain low costs communication. If the device remains anchored at the initial gateway, sub-optimal routing paths may be the result. Assignment of a new mobility gateway to a mobile device is referred to as “gateway relocation”.
One problem with the assignment of a new gateway is the demand for Internet Protocol (IP) session continuity. Since the mobile device's IP address is topologically anchored at the gateway, current technology assumes that the device remains anchored over a long period of time, while it's attached to the network infrastructure. A change in the mobility gateway of a mobile device implies a change in the device's IP address, which results in a broken IP session.
Current technology for DMM solves the problem of IP session—and IP address continuity by using a forwarding tunnel from the initial gateway to the device's current gateway. That is, the messages from the core network are first sent to the device's initial gateway, and are tunneled from there to the device's current gateway. This is inefficient, and creates further bandwidth demands on the network, but has the advantage that the IP address of the mobile device remains anchored at the initial gateway, so the IP session will not be broken. Some approaches to handle DMM using such conventional technology are provided by the IETF, for example in “A Summary of Distributed Mobility Management”, draft-kuntz-dmm-summary-01, of Aug. 11, 2011, and available at “http://tools.ietf.org/id/draft-kuntz-dmm-summary-01.txt”. Further information can be obtained from the IETF, for example in “DMM Comparison Matrix”, draft-perkins-dmm-matrix-01, of Jul. 9, 2011, available at “http://tools.ietf.org/id/draft-perkins-dmm-matrix-01.txt”, or “Approaches to Distributed mobility management using Mobile IPv6 and its extensions”, draft-patil-mext-dmm-approaches-01, of Jul. 12, 2011, available at “http://tools.ietf.org/id/draft-patil-mext-dmm-approaches-01.txt”.